Fixes graphql project stats

What does this MR do?

Fixes bug introduced on https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28277

The fix was originally developed on https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/3160, but since it was a security vulnerability introduced on %12.0, we decided to fix it on %12.0 before it's released.

AppSec team approved to release this on 12.0 on https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/3160#note_165993 and through slack

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/63275